User equipment, PDSCH A/N transmitting method thereof, transmission/reception point, and PDSCH A/N receiving method thereof

ABSTRACT

The present invention relates to a system that includes a transmission/reception point and a user equipment having different configurations in inter-band and performs a TDD (Time Division Duplex) method.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/061,508, filed on Oct. 1, 2020, which is a continuation of U.S.patent application Ser. No. 16/394,702, filed on Apr. 25, 2019, nowissued as U.S. Pat. No. 10,805,060, which is a continuation of U.S.patent application Ser. No. 15/800,561, filed on Nov. 1, 2017, which isa continuation of U.S. patent application Ser. No. 15/014,792, filed onFeb. 3, 2016, now issued as U.S. Pat. No. 9,838,194, which is acontinuation application of U.S. patent application Ser. No. 14/513,449,filed on Oct. 14, 2014, now issued as U.S. Pat. No. 9,270,365, which isa continuation application of U.S. patent application Ser. No.13/715,278, filed on Dec. 14, 2012, now issued as U.S. Pat. No.8,873,519, and claims priority from and the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2011-0136662, filed on Dec.16, 2011 and Korean Patent Application No. 10-2012-0009275, filed onJan. 30, 2012, all of which are hereby incorporated by reference for allpurposes as if fully set forth herein.

BACKGROUND 1. Field

The present disclosure relates to a system in which atransmission/reception point and a user equipment have differentconfigurations in an inter-band and perform communication by TDD (TimeDivision Duplex) method.

2. Discussion of the Background

As communication systems have been advanced, companies and consumerssuch as individuals come to use a great variety of wireless userequipments. The current mobile communication system of 3GPP series, suchas the LTE (Long Term Evolution), and LTE-A (LTE Advanced), requirestechnology developments capable of providing high-capacity dataequivalent to a wire communication network as a high-speed,large-capacity communication system that can transmit/receive variouskinds of data, such as moving images, and wireless data out of servicesdevoted to a sound. As a method for transmitting high-capacity data, amethod of effectively transmitting data through a large number ofcomponent carriers may be used.

Meanwhile, in a TDD (Time Division Duplex) system, it is possible totransmit and receive data by dividing transmission (Tx) or reception(Rx) into time slots and using specific frequency bands. In this scheme,timings for transmitting response information with respect to the datareception can be changed according to a method of configuring an uplink(UL) and a downlink (DL) in a TDD system.

Meanwhile, in a carrier aggregation (CA) environment for aggregating oneor more component carriers (CCs), a band corresponding to each componentcarrier can be different. That is, in inter-band carrier aggregationscheme, component carriers in different operating bands are aggregated.When the carrier aggregation is performed by an inter-band carrieraggregating method, if the TDD configurations of respective bands aredifferent, it should be considered for a timing at which the responseinformation with respect to the data reception is transmitted. Thetiming for transmitting the response information with respect to thedata reception should be able to be applied to both a scheme in whichthe user equipment is in a full-duplex mode and a scheme in which theuser equipment is in a half-duplex mode.

SUMMARY

Exemplary embodiments of the present invention provide a method and anapparatus for determining timings for transmitting response informationwith respect to data reception when two component carriers havedifferent TDD configurations in a carrier aggregation environment.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

Exemplary embodiments of the present invention provide a user equipmentthat is configured with at least two serving cells including a primarycell (PCell) and a secondary cell (SCell). The PCell and the SCell havedifferent TDD UL-DL configurations. The user equipment includes atransmitter configured to transmit first acknowledgement/negativeacknowledgement (A/N) in an uplink subframe determined by a referenceTDD configuration for the SCell. The first A/N corresponds to a PhysicalDownlink Shared Channel (PDSCH) transmission on the SCell. The referenceTDD configuration for the SCell has a greatest number of uplinksubframes from among one or more reference TDD configurations for theTDD UL-DL configurations of the PCell and the SCell in Table 1 below:

TABLE 1 Reference TDD PCell TDD UL-DL configuration configuration 0 1 23 4 5 6 SCell TDD 0 0 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 1, 2, 3, 4, 5, 6UL-DL configuration 1 1, 2, 4, 5 1 2, 5 4, 5 4, 5 5 1, 2, 4, 5 2 2, 5 2,5 2 5 5 5 2, 5 3 3, 4, 5 4, 5 5 3 4, 5 5 3, 4, 5 4 4, 5 4, 5 5 4, 5 4 54, 5 5 5 5 5 5 5 5 5 6 1, 2, 3, 4, 5, 6 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 6

in Table 1 above, each reference TDD configuration indicates downlinkassociation set indexes (K: {k₀, k₁, . . . k_(M-1)}) for a subframe ‘n’as defined in Table 2 below:

TABLE 2 UL-DL Subframe ‘n’ Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4— — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4,6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 —— — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 —— 7 7 —

where A/N corresponding to PDSCH transmitted in a subframe (n−k_(i))(0≤i≤M−1) is transmitted in the subframe ‘n’.

Exemplary embodiments of the present invention provide a method fortransmitting A/N by a user equipment configured with at least twoserving cells including a primary cell (PCell) and a secondary cell(SCell). The PCell and the SCell have different TDD UL-DLconfigurations. The method includes transmitting first A/N in an uplinksubframe determined by a reference TDD configuration for the SCell. Thefirst A/N corresponds to a physical downlink shared channel (PDSCH)transmission on the SCell. The reference TDD configuration for the SCellhas a greatest number of uplink subframes from among one or morereference TDD configurations for the TDD UL-DL configurations of thePCell and the SCell in Table 1 below:

TABLE 1 Reference TDD PCell TDD UL-DL configuration configuration 0 1 23 4 5 6 SCell TDD 0 0 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 1, 2, 3, 4, 5, 6UL-DL configuration 1 1, 2, 4, 5 1 2, 5 4, 5 4, 5 5 1, 2, 4, 5 2 2, 5 2,5 2 5 5 5 2, 5 3 3, 4, 5 4, 5 5 3 4, 5 5 3, 4, 5 4 4, 5 4, 5 5 4, 5 4 54, 5 5 5 5 5 5 5 5 5 6 1, 2, 3, 4, 5, 6 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 6

in Table 1 above, each reference TDD configuration indicates downlinkassociation set indexes (K: {k₀, k₁, . . . k_(M-1)}) for a subframe ‘n’as defined in Table 2 below:

TABLE 2 UL-DL Subframe ‘n’ Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4— — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4,6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 —— — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 —— 7 7 —

where A/N corresponding to PDSCH transmitted in a subframe (n−k_(i))(0≤i≤M−1) is transmitted in the subframe ‘n’.

Exemplary embodiments of the present invention provide atransmission/reception point that communicates with a user equipmentconfigured with at least two serving cells including a primary cell(PCell) and a secondary cell (SCell). The PCell and the SCell havedifferent TDD UL-DL configurations. The transmission/reception pointincludes a receiver configured to receive first A/N from the userequipment in an uplink subframe determined by a reference TDDconfiguration for the SCell. The first A/N corresponds to a physicaldownlink shared channel (PDSCH) transmission on the SCell. The referenceTDD configuration for the SCell has a greatest number of uplinksubframes from among one or more reference TDD configurations for theTDD UL-DL configurations of the PCell and the SCell in Table 1 below:

TABLE 1 Reference TDD PCell TDD UL-DL configuration configuration 0 1 23 4 5 6 SCell TDD 0 0 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 1, 2, 3, 4, 5, 6UL-DL configuration 1 1, 2, 4, 5 1 2, 5 4, 5 4, 5 5 1, 2, 4, 5 2 2, 5 2,5 2 5 5 5 2, 5 3 3, 4, 5 4, 5 5 3 4, 5 5 3, 4, 5 4 4, 5 4, 5 5 4, 5 4 54, 5 5 5 5 5 5 5 5 5 6 1, 2, 3, 4, 5, 6 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 6

in Table 1 above, each reference TDD configuration indicates downlinkassociation set indexes (K: {k₀, k₁, . . . k_(M-1)}) for a subframe ‘n’as defined in Table 2 below:

TABLE 2 UL-DL Subframe ‘n’ Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4— — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4,6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 —— — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 —— 7 7 —

where A/N corresponding to PDSCH transmitted in a subframe (n−k_(i))(0≤i≤M−1) is transmitted in the subframe ‘n’.

Exemplary embodiments of the present invention provide a method forreceiving A/N by a transmission/reception point that communicates with auser equipment configured with at least two serving cells including aprimary cell (PCell) and a secondary cell (SCell). The PCell and theSCell have different TDD UL-DL configurations. The method includesreceiving first A/N from the user equipment in an uplink subframedetermined by a reference TDD configuration for the SCell. The first A/Ncorresponds to a physical downlink shared channel (PDSCH) transmissionon the SCell. The reference TDD configuration for the SCell has agreatest number of uplink subframes from among one or more reference TDDconfigurations for the TDD UL-DL configurations of the PCell and theSCell in Table 1 below:

TABLE 1 Reference TDD PCell TDD UL-DL configuration configuration 0 1 23 4 5 6 SCell TDD 0 0 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 1, 2, 3, 4, 5, 6UL-DL configuration 1 1, 2, 4, 5 1 2, 5 4, 5 4, 5 5 1, 2, 4, 5 2 2, 5 2,5 2 5 5 5 2, 5 3 3, 4, 5 4, 5 5 3 4, 5 5 3, 4, 5 4 4, 5 4, 5 5 4, 5 4 54, 5 5 5 5 5 5 5 5 5 6 1, 2, 3, 4, 5, 6 1, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 6

in Table 1 above, each reference TDD configuration indicates downlinkassociation set indexes (K: {k₀, k₁, . . . k_(M-1)}) for a subframe ‘n’as defined in Table 2 below:

TABLE 2 UL-DL Subframe ‘n’ Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4— — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4,6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 —— — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 —— 7 7 —

where A/N corresponding to PDSCH transmitted in a subframe (n−k_(i))(0≤i≤M−1) is transmitted in the subframe ‘n’.

According to aspects of the present invention, if the TDD configurationsof two component carriers are different in a carrier aggregationenvironment, a timing for transmitting response information with respectto a data reception can be determined.

It is to be understood that both forgoing general descriptions and thefollowing detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a diagram illustrating a wireless communication systemaccording to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating an inter-band CA environment accordingto an exemplary embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of requiring different TDDUL-DL configurations in an inter-band in order to avoid an interferencewith different TDD systems according to an exemplary embodiment of thepresent invention.

FIG. 4 is a diagram illustrating an operation method of each subframewhen a user equipment in an inter-band CA environment of FIG. 2 is in ahalf-duplex mode according to an exemplary embodiment of the presentinvention.

FIG. 5 is a diagram illustrating an operation method for each subframewhen a user equipment in an inter-band CA environment of FIG. 2 is in afull-duplex mode.

FIG. 6 is a flowchart illustrating a method of configuring PDSCH A/Ntiming of a transmission/reception point according to an exemplaryembodiment of the present invention.

FIG. 7 is a diagram illustrating a PDSCH A/N transmitting method of auser equipment according to an exemplary embodiment of the presentinvention.

FIG. 8 , FIG. 9 , FIG. 10 , and FIG. 11 are diagrams illustratingexamples of a relation between a subframe transmitting PDSCH and asubframe transmitting PDSCH A/N at a PDSCH A/N timing according to anexemplary embodiment of the present invention.

FIG. 12 is a flowchart illustrating a method of configuring PDSCH A/Ntiming of a transmission/reception point according to an exemplaryembodiment of the present invention.

FIG. 13 is a diagram illustrating a method of transmitting PDSCH A/N ofa user equipment according to an exemplary embodiment of the presentinvention.

FIG. 14 and FIG. 15 are diagrams illustrating examples of a relationbetween a subframe transmitting PDSCH and a subframe transmitting PDSCHA/N at a PDSCH A/N timing according to an exemplary embodiment of thepresent invention.

FIG. 16 is a diagram illustrating a configuration of atransmission/reception point according to an exemplary embodiment of thepresent invention.

FIG. 17 is a diagram illustrating a configuration of a user equipmentaccording to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which exemplary embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth herein. Rather, these exemplary embodiments areprovided so that this disclosure is thorough, and will fully convey thescope of the invention to those skilled in the art. It will beunderstood that for the purposes of this disclosure, “at least one of X,Y, and Z” can be construed as X only, Y only, Z only, or any combinationof two or more items X, Y, and Z (e.g., XYZ, XZ, XYY, YZ, ZZ).Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals are understood to referto the same elements, features, and structures. The relative size anddepiction of these elements may be exaggerated for clarity.

FIG. 1 is a diagram illustrating a wireless communication systemaccording to an exemplary embodiment of the present invention.

The wireless communication system may provide various communicationservices, such as voice communications or packet data communications.

With reference to FIG. 1 , the wireless communication system includes auser equipment (UE) 10 and a transmission/reception point 20 thatperforms uplink and downlink communications with the user equipment 10.

In the present disclosure, the user equipment 10 may be a user equipmentin a wireless communication system, and it is to be understood that theuser equipment 10 includes a UE (User Equipment) in WCDMA, LTE, HSPA,and the like, and also includes an MS (Mobile Station), a UT (UserTerminal), a SS (Subscriber Station), a wireless device, or the like inGSM.

A transmission/reception point 20 or a cell generally refers to astation for communication with the user equipment 10, and it may be alsoreferred to as an access point (AP), a base station (BS), a node-B, aneNB (evolved Node-B), a sector, a site, a BTS (Base Transceiver System),an access point, a relay node, and the like.

That is, in the present specification, it is to be understood that thetransmission/reception point 20 or a cell may indicate a partial regionor function which is covered by a BSC (Base Station Controller) in acell or CDMA, a NodeB in WCDMA, or an eNB or a sector (site) in LTE, andthe transmission/reception point 20 may have various coverage regions,such as a megacell, a macrocell, a microcell, a pico cell, a femto cell,an RRH (Radio Resource Head), and a relay node communication range.

In the present disclosure, the user equipment 10 and thetransmission/reception point 20 are two exemplary communication devicesused for implementing a technology or a technical idea described in thepresent disclosure in uplink/downlink communications, and scope of theinvention is not limited by particularly designated terms or words forthe communication devices.

FIG. 1 illustrates one user equipment 10 and one transmission/receptionpoint 20, but aspects of the present invention are not limited thereto.One transmission/reception point 20 can communicate with a plurality ofthe user equipments 10, and also one user equipment 10 can communicatewith a plurality of the transmission/reception point 20.

Various multiple access communication methods may be applied to thewireless communication system. Various multiple access communicationmethods, such as CDMA (Code Division Multiple Access), TDMA (TimeDivision Multiple Access), FDMA (Frequency Division Multiple Access),OFDMA (Orthogonal Frequency Division Multiple Access), OFDM-FDMA,OFDM-TDMA, and OFDM-CDMA can be used. Exemplary embodiments of thepresent invention may be applied to the resource allocation forasynchronous wireless communication that evolves through GSM, WCDMA andHSPA to LTE and LTE-advanced, or synchronous wireless communication thatevolves to CDMA, CDMA-2000, and UMB, or the like. Exemplary embodimentsof the present invention are not to be limited to a particular wirelesscommunication field, and are to be construed to include all thetechnical fields to which the idea of the present invention can beapplied.

The uplink transmission and the downlink transmission may be performedby using a TDD (Time Division Duplex) method in which the transmissionsare performed at different timings or an FDD (Frequency Division Duplex)method in which the transmissions are performed at differentfrequencies.

With reference to FIG. 1 , the user equipment 10 and thetransmission/reception point 20 may perform uplink and downlink wirelesscommunications.

In the wireless communication, one wireless frame (radio frame) mayinclude 10 subframes, and one subframe may include two slots. Thewireless frame may have a duration of 10 ms, and the subframe may have aduration of 1.0 ms. In general, the base unit for data transmission intime domain may be one subframe, and downlink or uplink scheduling isperformed by the subframe unit.

The transmission/reception point 20 may perform a downlink transmissionto the user equipment 10. The transmission/reception point 20 maytransmit data via a physical downlink shared channel (PDSCH) as adownlink data channel for a unicast transmission. Further, thetransmission/reception point 20 may transmit a control channel, such asa physical downlink control channel (PDCCH) as a downlink channel usedfor transmitting downlink control information (DCI), such as ascheduling required for PDSCH reception, and downlink controlinformation (DCI) including scheduling grant information for atransmission in the uplink data channel (for example, a physical uplinkshared channel (PUSCH)), a physical control format indicator channel(PCFICH) for transmitting indicators that divide regions of PDSCH andPDCCH, and a physical HARQ indicator channel (PHICH) for transmittingthe HARQ (Hybrid Automatic Repeat request) confirmation on the uplinktransmission. Hereinafter, the transmission/reception of a signalthrough each channel will be described as transmitting/receiving thecorresponding channel.

The user equipment 10 may perform an uplink transmission to thetransmission/reception point 20. The user equipment 10 may transmitPUSCH as an uplink data channel. Further, the user equipment 10 maytransmit HARQ ACK (acknowledgement)/NACK (negative ACK) indicatingwhether the downlink transmission block is successfully received and aphysical uplink control channel (PUCCH) as an uplink control channelused for transmitting uplink control information (UCI) including ascheduling request that demands resource allocation if the channel statereport and the uplink data transmission is desired.

Meanwhile, in TDD, time points for uplink and downlink are divided, andif there are various TDD configurations, the points may vary.

Table 1 presents a TDD configuration. Each TDD configuration hasdifferent UL-DL (Uplink-Downlink) subframe transmission timing. Such aTDD configuration may be a cell-specific configuration.

TABLE 1 Uplink-downlink Downlink-to-Uplink Subframe number configurationSwitch-point periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  D S U U UD D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D D D D 6 5ms D S U U U D S U U D

In Table 1, in radio frame corresponding to 10 subframes, regionsindicated by D represent downlink subframes, and regions indicated by Urepresents uplink subframes. S represents a subframe that switches fromdownlink to uplink (Downlink-to-Uplink Switch-point). For example, if aTDD UL-DL (uplink-downlink) configuration is 1, a subframe having asubframe number 0, 4, 5, or 9 is a downlink subframe, a subframe havinga subframe number 2, 3, 7, or 8 is an uplink subframe, and a subframehaving a subframe number 1 or 6 is a subframe that switches fromdownlink to uplink.

Meanwhile, if one of the TDD UL-DL configurations is used, the userequipment can know in advance uplink points and downlink points. Suchinformation enables the user equipment to perform operations in advanceby predicting the uplink, downlink, and switching subframes.

A response for a downlink data transmission, e.g., A/N (Ack/Nack) forPDSCH, is transmitted through an uplink frame from the user equipment 10to the transmission/reception point 20. For an uplink subframe in whichA/N for PDSCH is transmitted from the user equipment 10, downlinkassociation set indexes (K: {k₀, k₁, . . . k_(M-1)}) indicate anassociation value associated with a downlink subframe in which the PDSCHis transmitted to the user equipment 10. For each UL-DL configuration,the downlink association set indexes ‘K’ for an uplink subframe ‘n’ areshown in Table 2 below.

TABLE 2 UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 —— 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6— — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — —— — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — —7 7 —

For an uplink subframe ‘n’ in each TDD UL-DL configuration, an indexk_(i) in Table 2 indicates the number of subframes counted from theuplink subframe (subframe ‘n’) for transmitting A/N for PDSCH to adownlink subframe, which is located before the uplink subframe, fortransmitting the PDSCH. That is, with respect to the PDSCH transmittedin the downlink subframe (n−k) (k∈K), A/N for the PDSCH is transmittedin an uplink subframe ‘n’. For example, it is assumed that a TDD UL-DLconfiguration is 1. If a subframe number ‘n’ is 2, and K={7, 6}, A/N forPDSCH transmitted in downlink subframes having subframe numbers 5 and 6in the previous radio frame is transmitted through the subframe ‘2’. (Ifone radio frame includes ten subframes from subframe 0 to subframe 9,the subframe numbers 5 and 6 in the previous radio frame correspond to‘2−7’=−5 and ‘2−6’=−4, respectively). If a subframe number ‘n’ is 3, andK={4}, A/N for PDSCH transmitted in a downlink subframe having thesubframe number 9 in the previous radio frame is transmitted in thesubframe ‘3’. If a subframe number ‘n’ is 7, and K={7, 6}, A/N for PDSCHtransmitted in downlink subframes having subframe numbers 0 and 1 of thesame radio frame is transmitted in the subframe ‘7’. Further, when thesubframe number is 8, and K={4}, A/N of PDSCH transmitted in a downlinksubframe having a subframe number 4 of the same radio frame istransmitted through the subframe ‘8’.

Meanwhile, in a carrier aggregation (CA) environment in which one ormore component carriers (CC) are aggregated, bands including respectivecomponent carriers may be different. If the carrier aggregation isperformed by an inter-band method, a TDD configuration for each band maybe different from each other. However, carrier waves included in bandshaving different TDD configurations may be used in one user equipment.

FIG. 2 is a diagram illustrating an inter-band CA environment accordingto an exemplary embodiment of the present invention.

It is illustrated that two component carriers are configured in a system210, where a CC1 211 is a carrier wave that has a coverage of ahigh-powered signal transmitted from an eNB, and the CC2 212 is acarrier wave that has a coverage of a low-powered signal transmittedfrom the eNB. The CC1 211 and the CC2 212 may be included in differentbands. The TDD UL-DL configuration of the CC1 211, which is denoted by“1” in Table 1, is denoted by “281” in FIG. 2 , and the TDD UL-DLconfiguration of the CC2 212, which is denoted by “2” in Table 1, isdenoted by “282” in FIG. 2 . In this environment, a CA configuration maybe possible for user equipments located in the coverage of CC2 212.Further, a hot-spot region 215 may be configured by the CA environmentof the CC1 211 and the CC2 212.

In the CA environment, the user equipment that communicates with thetransmission/reception point may perform a communication via CCs thathave different TDD configurations (for example, the CC1 211 and the CC2212).

For example, different TDD UL-DL configurations may be used ininter-band for the purpose of traffic adaptation.

In another example, with reference to FIG. 3 , the TDD uplink-downlinkof a TDD system (for example, the LTE-A 330 and 340) is configured inorder to avoid interferences with different TDD systems (for example,the TDS-CDMA 310 or the LTE 320) that exist in a same band, so differentTDD UL-DL configurations may be applied for the TDD system in theinter-band. That is, in the example of FIG. 3 , in a band A 410, theLTE-A 330 has a TDD UL-DL configuration of “2” in order to avoid aninterference with the TDS-CDMA 310, and in a band B 420, the LTE-A 340has a TDD UL-DL configuration of “0” in order to avoid an interferencewith the LTE 320, so the LTE-A 330 and the LTE-A 340 that are located indifferent bands may have different TDD UL-DL configurations.

Further, in a low frequency band, a TDD UL-DL configuration having moreuplink subframes may be used, and in a high frequency band, a TDD UL-DLconfiguration having more downlink subframes may be used. Thisconfiguration may enhance the coverage increase.

The examples described above may influence the peak throughput.

In this case, the operation method may be different subframe by subframedepending on whether the transmission mode, which can be supported on aconflicting subframe, is a half-duplex mode or a full-duplex mode. Theconflicting subframe may occur if a user equipment adopts different TDDconfigurations in the inter-band configuration.

FIG. 4 is a diagram illustrating operation methods for each subframewhen a transmission mode is a half-duplex mode in a conflicting subframethat may occur if a user equipment adopts different TDD configurationsin the inter-band configuration in an inter-band CA environment of FIG.2 . In the example of FIG. 4 , a PCell (Primary Cell) has a TDD UL-DLconfiguration “1” and an SCell (Secondary Cell) has a TDD UL-DLconfiguration “2”. In FIG. 4 , U denotes a subframe dedicated for anuplink transmission, D denotes a subframe dedicated for a downlinktransmission, and S denotes a special subframe in which a downlinktransmission switches to an uplink transmission.

With reference to FIG. 4 , if the subframe number is 3 or 8, the PCellhas an uplink configuration, and the SCell has a downlink configuration.Hereinafter, the subframes in which the CCs have differentuplink/downlink are referred to as conflicting subframes. Since the userequipment is in a half-duplex mode, at least one of an uplink subframeof the PCell and a downlink subframe of the SCell operates as a mutedsubframe. In the example of FIG. 4 , when the subframe number is 3 or 8,the uplink subframe of the PCell is a muted subframe.

A physical uplink control channel (PUCCH) that includes A/N for PDSCH(PDSCH A/N) may be transmitted only by the PCell. Hereinafter, A/N forPDSCH (A/N with respect to PDSCH) may be referred to as ‘PDSCH A/N’. Ifan uplink subframe in a PCell for transmitting PDSCH A/N is a mutedsubframe, an event in which the PDSCH A/N cannot be transmitted in theuplink subframe may occur.

In the example of FIG. 4 , since the TDD UL-DL configuration of thePCell is “1”, PDSCH A/N can be transmitted in a subframe when thesubframe number is 2, 3, 7, or 8, with reference to Table 2. However,when the subframe number is 3 or 8, if the uplink subframe of CC1 is amuted subframe, PDSCH A/N cannot be transmitted in the subframe havingthe subframe number 3 for PDSCH transmitted in a downlink subframehaving the subframe number 9 in the previous radio frame, and PDSCH A/Ncannot be transmitted in the subframe having the subframe number 8 forPDSCH transmitted in a downlink subframe having the subframe number 4 ofthe same radio frame.

FIG. 5 is a diagram illustrating an operation method for each subframewhen a user equipment in an inter-band CA environment is in afull-duplex mode. In FIG. 5 , a PCell has a TDD UL-DL configuration “1”and an SCell has a TDD UL-DL configuration “2”. In FIG. 5 , U denotes asubframe dedicated for an uplink transmission, D denotes a subframededicated for a downlink transmission, and S denotes a special subframein which a downlink transmission switches to an uplink transmission.

With reference to FIG. 5 , when the subframe number is 3 or 8, the PCellhas an uplink configuration and the SCell has a downlink configuration.Since the user equipment is in a full-duplex mode in a conflictingsubframe that may occur if the user equipment adopts different TDDconfigurations in the inter-band configuration, the user equipment maytransmit an uplink signal through the PCell even in the conflictingsubframe and receive a downlink signal through the SCell even in theconflicting subframe simultaneously. The PUCCH including PDSCH A/N maybe transmitted only through the PCell. However, an event in which PDSCHA/N cannot be transmitted for PDSCH transmitted in a specific downlinksubframe may occur.

In the example of FIG. 5 , since the TDD UL-DL configuration of thePCell is “1”, PDSCH A/N can be transmitted in a subframe when thesubframe number is 2, 3, 7, or 8, with reference to Table 2. Morespecifically, with reference to Table 2, when the uplink subframe numberis 2, K={7, 6}. Thus, PDSCH A/N can be transmitted in the uplinksubframe ‘2’ for PDSCH transmitted in a downlink subframe having asubframe number 5 or 6 of the previous radio frame. When the uplinksubframe number is 3, K={4}. Thus, PDSCH A/N can be transmitted in theuplink subframe ‘3’ for PDSCH transmitted in a downlink subframe havinga subframe number 9 of the previous radio frame. When the uplinksubframe number is 7, K={7, 6}, so the PDSCH A/N can be transmitted inthe uplink subframe ‘7’ for PDSCH transmitted in a downlink subframehaving a subframe number 0 or 1 of the same radio frame. When the uplinksubframe number is 8, K={4}. Thus, PDSCH A/N can be transmitted in theuplink subframe ‘8’ for PDSCH transmitted in a downlink subframe havinga subframe number 4 of the same radio frame. In a nutshell, through thesubframe numbers 2, 3, 7, and 8, PDSCH A/N can be transmitted for PDSCHtransmitted in a downlink subframe having a subframe number 0, 1, 4, 5,6, or 9.

Meanwhile, since the TDD UL-DL configuration of the SCell is “2”, PDSCHcan be transmitted by a downlink transmission in a subframe when thesubframe number is 0, 1, 3, 4, 5, 6, 8, or 9, with reference to Table 2.Among the subframes having the subframe number 0, 1, 3, 4, 5, 6, 8, or9, for PDSCH transmitted in the subframe number 0, 1, 4, 5, 6, or 9,PDSCH A/N can be transmitted in the uplink subframes 2, 3, 7, and 8 ofthe PCell. However, for PDSCH transmitted in the subframe number 3 or 8of the SCell, PDSCH A/N cannot be transmitted in an uplink subframe ofthe PCell.

As described above, when a plurality of CCs use different TDD UL-DLconfigurations, a problem in that PDSCH A/N scheduling according toTable 2 cannot be used may occur.

FIG. 6 is a flowchart illustrating a method of configuring PDSCH A/Ntiming of a transmission/reception point according to an exemplaryembodiment of the present invention.

With reference to FIG. 6 , the method of configuring PDSCH A/N timing ofthe transmission/reception point may include comparing two different TDDUL-DL configurations configured in a PCell and an SCell, respectively(S610), searching for one or more common uplink subframes from the twoTDD UL-DL configurations (S620), identifying one or more reference TDDconfigurations that satisfy a condition that a set including uplinksubframes of a reference TDD configuration for transmitting PDSCH A/N isa subset of a set including the one or more common uplink subframesdetermined in the operation S620 (S630), selecting a specific referenceTDD configuration for a user equipment from the one or more referenceTDD configurations (S640), and transmitting the specific reference TDDconfiguration to the user equipment (S650).

With reference to FIG. 6 , the transmission/reception point compares twoor more different TDD UL-DL configurations configured in a PCell and anSCell in operation S610. Hereinafter, an example of two different TDDUL-DL configurations will be described.

Next, the transmission/reception point searches for a common uplinksubframe from the two TDD UL-DL configurations in operation S620. Forexample, when the TDD UL-DL configuration of the PCell is “0” and theTDD UL-DL configuration of the SCell is “1”, an uplink subframe in thePCell has a subframe number 2, 3, 4, 7, 8, or 9, and an uplink subframein the SCell has a subframe number 2, 3, 7, or 8. Therefore, the commonuplink subframes are uplink subframes having subframe numbers 2, 3, 7,and 8.

Next, the transmission/reception point identifies one or more referenceTDD configurations that satisfy a condition that a set including uplinksubframes of a reference TDD configuration for transmitting PDSCH A/N isa subset of a set including the common uplink subframes from Table 2 inoperation S630.

In the present disclosure, the reference TDD configuration is not forconfiguring uplink and downlink timing of a PCell or one or more SCells(See Table 1), but for configuring PDSCH A/N transmission timing of thePCell or the SCells (See Table 2). Based on the timing configured inthis manner, PDSCH A/N information is transmitted through an uplinkcontrol channel on the PCell in the determined uplink subframe.

For example, it is assumed that the subframe numbers of the commonuplink subframe are 2, 3, 7, and 8 as illustrated above. With referenceto Table 2, when the TDD configuration is 1, PDSCH A/N can betransmitted in the subframe number 2, 3, 7, or 8; when the TDDconfiguration is 2, PDSCH A/N can be transmitted in the subframe number2 or 7; when the TDD configuration is 4, PDSCH A/N can be transmitted inthe subframe number 2 or 3; and when the TDD configuration is 5, PDSCHA/N can be transmitted in the subframe number 2. Therefore, the TDDconfigurations 1, 2, 4, and 5 can be reference TDD configurationsbecause a set including uplink subframes of TDD configurations 1, 2, 4,or 5 is a subset of a set including the common uplink subframes 2, 3, 7,and 8.

However, when the TDD configuration is 0, PDSCH A/N can be transmittedin a subframe having the subframe number 2, 4, 7, or 9, and among thesubframes 2, 4, 7, and 9, the subframe numbers 4 and 9 do not belong tothe set including the common uplink subframes. When the TDDconfiguration is 3, PDSCH A/N can be transmitted in a subframe havingthe subframe number 2, 3, or 4, and among the subframes 2, 3, and 4, thesubframe number 4 does not belong to the set including the common uplinksubframes. When the TDD configuration is 6, PDSCH A/N can be transmittedin a subframe having the subframe number 2, 3, 4, 7, or 8, and among thesubframes 2, 3, 4, 6, and 8, the subframe number 4 does not belong tothe set including the common uplink subframes. Therefore, the TDDconfigurations 0, 3, and 6 are excluded from the reference TDDconfiguration.

Table 3 shows an example of reference TDD configurations (“referencePDSCH A/N timing”) possible to all the TDD UL-DL configurationcombinations of a PCell and an SCell. In Table 3, cases in that the TDDUL-DL configurations of the PCell and the SCell are the same are notdescribed in the present disclosure.

TABLE 3 Reference TDD configuration (Reference PDSCH PCell TDD UL-DLconfiguration A/N Timing) 0 1 2 3 4 5 6 SCell TDD 0 0 1, 2, 4, 5 2, 5 3,4, 5 4, 5 5 1, 2, 3, 4, 5, 6 UL-DL configuration 1 1, 2, 4, 5 1 2, 5 4,5 4, 5 5 1, 2, 4, 5 2 2, 5 2, 5 2 5 5 5 2, 5 3 3, 4, 5 4, 5 5 3 4, 5 53, 4, 5 4 4, 5 4, 5 5 4, 5 4 5 4, 5 5 5 5 5 5 5 5 5 6 1, 2, 3, 4, 5, 61, 2, 4, 5 2, 5 3, 4, 5 4, 5 5 6

The transmission/reception point can find one or more reference TDDconfigurations through the operations S610 to S630.

Further, the transmission/reception point may store informationillustrated in e.g., Table 3, which is obtained by applying theoperations S610 to S630 for all possible cases, in advance. In thiscase, the transmission/reception point finds one or more reference TDDconfigurations from Table 3 based on the TDD UL-DL configuration of aPCell and the TDD UL-DL configuration of an SCell instead of performingoperations S610 to S630.

With reference to FIG. 6 , the transmission/reception point may select aspecific reference TDD configuration for a user equipment from one ormore reference TDD configuration in operation S640.

For example, if a channel environment of the corresponding userequipment is not good (for example, when the user equipment is locatedon the border of cells, or an SNR (Signal to Noise Ratio) is low), itmay be advantageous that the user equipment has as many PDSCH A/Ntimings as possible. This is because more credible A/N transmission issecured if more uplink subframes are provided such that PDSCH A/Ntimings are configured by reducing the amount of A/N information(Ack/Nack information) transmitted in one uplink subframe as much aspossible, that is, by reducing the number of PDSCH A/Ns for PDSCHstransmitted in the downlink subframes to be transmitted in one uplinksubframe as much as possible. Therefore, if the channel environment ofthe corresponding user equipment is not good, the transmission/receptionpoint may select a reference TDD configuration having as many uplinksubframes for PDSCH A/N timings as possible.

Meanwhile, if the channel environment of the corresponding userequipment is good (for example, when the user equipment is located inthe center of a cell, or an SNR is high), it may be advantageous thatthe user equipment has as few PDSCH A/N timings as possible. Moreinformation may be transmitted with less electric power using a fewernumber of uplink subframes if the channel environment is good. When theuplink PUCCH transmits PDSCH A/N and other information, e.g., UCI(Uplink Control Information), at the same time, PDSCH A/N, which isrelatively more important, is transmitted and relatively less importantinformation, such as CSI (Channel State Information), may not betransmitted. If there are few uplink subframes for transmitting PDSCHA/N in a reference TDD configuration, the possibility of dropping atransmission of relatively less important information, such as CSI, maybe reduced. Therefore, if the channel environment of the correspondinguser equipment is good, the transmission/reception point may select areference TDD configuration that has as few uplink subframes for PDSCHA/N timings as possible.

For example, it is assumed that one or more reference TDD configurationsare TDD configurations 1, 2, 4, and 5. When the reference TDDconfiguration is 1, the PDSCH A/N timings correspond to uplink subframenumbers 2, 3, 7, and 8 (the number of subframes for uplink is 4). Whenthe reference TDD configuration is 2, the PDSCH A/N timings correspondto uplink subframe numbers 2 and 7 (the number of subframes for uplinkis 2). When the reference TDD configuration is 4, the PDSCH A/N timingscorrespond to the uplink subframe numbers 2 and 3 (the number of thesubframes for uplink is 2). When the reference TDD configuration is 5,the PDSCH A/N timings correspond to the uplink subframe number 2 (thenumber of subframes for uplink is 1). Therefore, when a channelenvironment is good, the reference TDD configuration may be selected asthe reference TDD configuration 5; when a channel environment is bad,the reference TDD configuration may be selected as the reference TDDconfiguration 1; and when a channel environment is normal, the referenceTDD configuration may be selected as the reference TDD configuration 2or 4.

Further, the transmission/reception point may select a reference TDDconfiguration specific to a user equipment in consideration ofsimultaneous transmission and collision with other information orsignals (for example, CSI) transmitted through uplink. For example, thetransmission/reception point may configure PDSCH A/N transmission timing(and/or UCI transmission timing) so that a subframe in which PDSCH A/Nis transmitted through PUCCH and a subframe in which CSI is transmittedthrough PUCCH are not overlapped with each other. Further, thetransmission/reception point may configure PDSCH A/N transmissiontimings (and/or Sounding Reference Symbol (SRS) transmission timings) sothat a subframe in which PDSCH A/N is transmitted through PUCCH and asubframe in which SRS is transmitted through PUCCH are not overlappedwith each other.

Referring back to FIG. 6 , the transmission/reception point may transmitthe reference TDD configuration specific to the user equipment to thecorresponding user equipment in operation S650. The reference TDDconfiguration specific to the user equipment can be transmitted to theuser equipment through, e.g., RRC (Radio Resource Control) or PDCCH.

The information transmitted from the transmission/reception point to theuser equipment can be a value of a reference TDD configuration. Forexample, when the TDD UL-DL configuration of the PCell is 1, the TDDUL-DL configuration of the SCell is 2, and the reference TDDconfiguration is 5, the transmission/reception point may transmit thereference TDD configuration 5.

Further, the information transmitted from the transmission/receptionpoint to the user equipment may be an offset of the reference TDDconfiguration from the TDD UL-DL configuration of the PCell or theSCell. For example, when the TDD UL-DL configuration of the PCell is 1,the TDD UL-DL configuration of the SCell is 2, and the reference TDDconfiguration is 5, the transmission/reception point may transmit anoffset 4, which is the offset of the reference TDD configuration fromthe TDD UL-DL configuration of the PCell.

Further, the information transmitted from the transmission/receptionpoint to the user equipment may be an index of the reference TDDconfiguration specific to the user equipment among one or more possiblereference TDD configurations. For example, when the TDD UL-DLconfiguration of the PCell is 1, and the TDD UL-DL configuration of theSCell is 2, the one or more possible reference TDD configurations are 2and 5 with reference to Table 3. In this case, the index 1 may beassigned to the TDD configuration 2, and the index 2 may be assigned tothe TDD configuration 5. When the reference TDD configuration specificto the user equipment is determined as 5, the transmission/receptionpoint can transmit the index 2 that indicates the reference TDDconfiguration 5.

FIG. 7 is a diagram illustrating a PDSCH A/N transmitting method of auser equipment according to an exemplary embodiment of the presentinvention.

With reference to FIG. 7 , the PDSCH A/N transmitting method of the userequipment may include receiving reference TDD configuration informationfrom a transmission/reception point (S710), and transmitting PDSCH A/Nin a subframe selected based on the reference TDD configurationinformation (S720).

The user equipment has configurations associated with a PCell and anSCell in a CA environment, and has information of the TDD UL-DLconfigurations of the PCell and the SCell through an upper layersignaling, such as system information (SI) and RRC.

The user equipment may receive the reference TDD configurationinformation from the transmission/reception point in operation S710. Thereference TDD configuration information may be transmitted through RRCor PDCCH. The reference TDD configuration information may be the valueof the reference TDD configuration, the offset of the reference TDDconfiguration from the UL-DL TDD configuration of the PCell or theSCell, or the index of the reference TDD configuration.

The user equipment may determine the uplink subframes (timings) of thePCell for transmitting PDSCH A/N based on the reference TDDconfiguration information and Table 2, determine specific PDSCH A/N foreach of the determined uplink subframes in which the determined specificPDSCH A/N to be transmitted (the specific PDSCH A/N is A/N for PDSCHtransmitted in a specific downlink subframe of the PCell and/or theSCell), and transmit the PDSCH A/N in the corresponding uplink subframein operation S720.

More specifically, the user equipment may determine an uplink subframeof a PCell for transmitting PDSCH A/N based on the reference TDDconfiguration information and Table 2. Using the downlink associationset index(es) (K) of Table 2, specific PDSCH A/N to be transmitted ineach of the determined uplink subframes may be determined (the specificPDSCH A/N is A/N for PDSCH transmitted in a specific downlink subframe).For example, if the index of the determined uplink subframe for PDSCHA/N transmission is ‘n’, the PDSCH A/N for PDSCH transmitted in the(n−k) (k e K) subframe may be transmitted in the uplink subframe ‘n’. Ifthe (n−k) subframe is not a subframe (downlink subframe (D) or a specialsubframe (S)) that performs downlink transmission (when the userequipment is in a half-duplex mode or a full-duplex mode), or if the(n−k) subframe is muted (when the user equipment is in the half-duplexmode), PDSCH is not transmitted in the subframe, and therefore PDSCH A/Nfor PDSCH corresponding to the (n−k) subframe may not be transmittedregardless of the configuration of Table 2.

For example, it is assumed that the TDD UL-DL configuration of the PCellis 0, and the TDD UL-DL configuration of the SCell is 1. In this case,the UL-DL configuration of the PCell is ‘DSUUUDSUUU’, and the UL-DLconfiguration of the SCell is ‘DSUUDDSUUD’, and the subframes 4 and 9are conflicting subframes. With reference to Table 3, in this case, thereference TDD configuration may be one of 1, 2, 4, and 5.

FIG. 8 is a diagram illustrating an example in that the TDD UL-DLconfiguration of the PCell is 0, the TDD UL-DL configuration of theSCell is 1, and the reference TDD configuration is 1. When the referenceTDD configuration is 1, with reference to Table 2, when n=2, K={7, 6},when n=3, K={4}, when n=7, K={7, 6}, and when n=8, K={4}.

In the subframe 2 of the PCell in each radio frame, A/N for PDSCH may betransmitted with respect to the PDSCH transmissions in the subframes 5and 6 of the PCell in the previous radio frame and the PDSCHtransmissions in the subframes 5 and 6 of the SCell in the previousradio frame.

Further, in the subframe 3 of the PCell in each radio frame, A/N forPDSCH may be transmitted with respect to the PDSCH transmissions in thesubframe 9 of the SCell in the previous radio frame. Since subframe 9 ofthe PCell is an uplink subframe, the PDSCH A/N for PDSCH correspondingto the subframe 9 of the PCell is not transmitted in the subframe 3 ofthe PCell in the next radio frame. If the user equipment is in ahalf-duplex mode and the subframe 9 of the SCell is muted, PDSCH A/N forPDSCH corresponding to the subframe 9 of the SCell may not betransmitted because of the muted state of the subframe 9 of the SCell.

In the subframe 7 of the PCell in each radio frame, PDSCH A/N may betransmitted with respect to the PDSCH transmissions in the subframes 0and 1 of the PCell and the PDSCH transmissions in the SCell in the sameradio frame.

In the subframe 8 of the PCell in each radio frame, PDSCH A/N may betransmitted with respect to the PDSCH transmission in the subframe 4 ofthe SCell in the same radio frame. Since the subframe 4 of the PCell isan uplink subframe, PDSCH A/N for PDSCH corresponding to the subframe 4of the PCell is not transmitted in the subframe 8 of the PCell in thesame radio frame. If the user equipment is in a half-duplex mode and thesubframe 4 of the SCell is muted, PDSCH A/N for PDSCH corresponding tothe subframe 4 of the SCell may not be transmitted because of the mutedstate of the subframe 4 of the SCell.

FIG. 9 is a diagram illustrating an example in which the TDD UL-DLconfiguration of the PCell is 0, the TDD UL-DL configuration of theSCell is 1, and the reference TDD configuration is 2. If the referenceTDD configuration is 2, when n=2, K={8, 7, 4, 6}; and when n=7, K={8, 7,4, 6}, with reference to Table 2.

In the subframe 2 of the PCell in each radio frame, PDSCH A/N may betransmitted with respect to the PDSCH transmissions in the subframes 5and 6 of the PCell in the previous radio frame. Since the subframes 4and 8 of the PCell in the previous radio frame are uplink subframes,PDSCH A/N for PDSCH corresponding to the subframes 4 or 8 of the PCellmay not be transmitted. Further, in the subframe 2 of the PCell in eachradio frame, PDSCH A/N may be transmitted with respect to the PDSCHtransmissions in the subframes 4, 5, and 6 of the SCell in the previousradio frame. Since the subframe 8 of the SCell is an uplink subframe,PDSCH A/N for PDSCH corresponding to the subframe 8 of the SCell is nottransmitted. If the user equipment is in a half-duplex mode and thesubframe 4 of the SCell is muted, PDSCH A/N for PDSCH corresponding tothe subframe 4 of the SCell may not be transmitted because of the mutedstate of the subframe 4 of the SCell.

In the subframe 7 of the PCell in each radio frame, PDSCH A/N may betransmitted with respect to the PDSCH transmissions in the subframes 0and 1 of the PCell in the same radio frame. Since the subframe 9 of thePCell in the previous radio frame and the subframe 3 of the PCell in thesame radio frame are uplink subframes, PDSCH A/N for PDSCH correspondingto the subframes 9 and 3 of the PCell are not transmitted. Further,PDSCH A/N with respect to the PDSCH transmissions in the subframes 9 (inthe previous radio frame), 0, and 1 of the SCell may be transmitted inthe subframe 7 of the PCell. Since the subframe 3 of the SCell is anuplink subframe, PDSCH A/N for PDSCH corresponding to the subframe 3 ofthe SCell is not transmitted. If the user equipment is in a half-duplexmode and the subframe 9 of the SCell is muted, PDSCH A/N for PDSCHcorresponding to the subframe 9 of the SCell may not be transmittedbecause of the muted state of the subframe 9 of the SCell.

FIG. 10 is a diagram illustrating an example in which the TDD UL-DLconfiguration of the PCell is 0, the TDD UL-DL configuration of theSCell is 1, and the reference TDD configuration is 4. If the referenceTDD configuration is 4, when n=2, K={12, 8, 7, 11}; and when n=3, K={6,5, 4, 7}, with reference to Table 2.

In the subframe 2 of the PCell in each radio frame, PDSCH A/N may betransmitted with respect to the PDSCH transmissions in the subframes 0,1, and 5 of the PCell in the previous radio frame. Since the subframe 4of the PCell in the previous radio frame is an uplink subframe, PDSCHA/N for PDSCH corresponding to the subframe 4 of the PCell is nottransmitted. Further, in the subframe 2 of the PCell in each radioframe, PDSCH A/N may be transmitted with respect to the PDSCHtransmissions in the subframes 0, 1, 4, and 5 of the SCell in theprevious subframe. If the user equipment is in a half-duplex mode andthe subframe 4 of the SCell is muted, PDSCH A/N for PDSCH correspondingto the subframe 4 of the SCell may not be transmitted because of themuted state of the subframe 4 of the SCell.

In the subframe 3 of the PCell in each radio frame, PDSCH A/N may betransmitted with respect to the subframe 6 of the PCell in the previousradio frame. Since the subframes 7, 8, and 9 of the PCell in theprevious radio frame are uplink subframes, PDSCH A/N for PDSCHcorresponding to the subframes 7, 8, or 9 of the PCell is nottransmitted. Further, in the subframe 3 of the PCell, PDSCH A/N may betransmitted with respect to the subframes 6 and 9 of the SCell in theprevious radio frame. Since the subframes 7 and 8 of the SCell in theprevious radio frame are uplink subframes, PDSCH A/N for PDSCHcorresponding to the subframe 7 or 8 of the SCell is not transmitted. Ifthe user equipment is in a half-duplex mode and the subframe 9 of theSCell is muted, PDSCH A/N for PDSCH corresponding to the subframe 9 ofthe SCell may not be transmitted because of the muted state of thesubframe 9 of the SCell.

FIG. 11 is a diagram illustrating an example in which the TDD UL-DLconfiguration of the PCell is 0, the TDD UL-DL configuration of theSCell is 1, and the reference TDD configuration is 5. If the referenceTDD configuration is 5, when n=2, K={13, 12, 9, 8, 7, 5, 4, 11, 6} withreference to Table 2.

In the subframe 2 of the PCell in each radio frame, PDSCH A/N may betransmitted with respect to the PDSCH transmissions in the subframes 0,1, 5, and 6 of the PCell in the previous radio frame. Since thesubframes 3, 4, 7, and 8 of the PCell in the previous radio frame andthe subframe 9 of the PCell in the radio frame immediately before theprevious radio frame are uplink subframes, PDSCH A/N for PDSCHcorresponding to the subframes 9, 3, 4, 7, or 8 of the PCell is nottransmitted. Further, in the subframe 2 of the PCell in each radioframe, PDSCH A/N may be transmitted with respect to the PDSCHtransmissions in the subframe 0, 1, 4, 5, and 6 of the SCell in theprevious radio frame and the subframe 9 of the SCell in the radio frameimmediately before the previous radio frame. Since the subframes 3, 7,and 8 of the SCell in the previous radio frame are uplink subframes,PDSCH A/N for PDSCH corresponding to the subframes 3, 7, or 8 of theSCell is not transmitted. If the user equipment is in a half-duplexmode, and the subframes 4 and 9 of the SCell are muted, PDSCH A/N forPDSCH corresponding to the subframes 4 or 9 of the SCell may not betransmitted because of the muted state of the subframes 4 and 9 of theSCell.

Further, according to aspects of the present invention, HARQ timings canbe independently applied to respective PCell and SCell.

FIG. 12 is a flowchart illustrating a method of configuring PDSCH A/Ntiming of a transmission/reception point according to an exemplaryembodiment of the present invention.

With reference to FIG. 12 , a method of configuring PDSCH A/N timings ofthe transmission/reception point includes comparing the TDD UL-DLconfigurations of a PCell and one or more SCells (S1210), searching forone or more SCell reference TDD configurations that satisfy a conditionthat a set including uplink subframes of an SCell reference TDDconfiguration for PDSCH A/N transmission is a subset of a set includinguplink subframes of the PCell (S1220), selecting an SCell reference TDDconfiguration specific to a user equipment from the SCell reference TDDconfigurations (S1230), and transmitting the SCell reference TDDconfiguration specific to the user equipment to the user equipment(S1240).

With reference to FIG. 12 , the transmission/reception point comparestwo or more different TDD UL-DL configurations configured in a PCell andone or more SCells in operation S1210. Hereinafter, a description willbe made with reference to a case in which the TDD UL-DL configurationsare different between one PCell and one SCell, for example, but aspectsof the present invention are not limited thereto.

Next, the transmission/reception point identifies one or more SCellreference TDD configurations that satisfy a condition that a setincluding uplink subframes of an SCell reference TDD configuration forPDSCH A/N transmission is a subset of a set including uplink subframesof the PCell in operation S1220.

For example, if the TDD UL-DL configuration of the PCell is “1” and theTDD UL-DL configuration of the SCell is “2”, the uplink subframe in thePCell has the subframe numbers 2, 3, 7, and 8. With reference to Table2, if TDD UL-DL configuration is “1”, the PDSCH A/N can be transmittedin the subframe number 2, 3, 7, or 8; if the TDD UL-DL configuration is“2”, PDSCH A/N can be transmitted in the subframe number 2 or 7; if theTDD UL-DL configuration is “4”, PDSCH A/N can be transmitted in thesubframe number 2 or 3; and if the TDD UL-DL configuration is “5”, PDSCHA/N can be transmitted in the subframe number 2. Therefore, the TDDUL-DL configurations 1, 2, 4, and 5 can be SCell reference TDDconfigurations.

In another example, if the TDD UL-DL configuration of the PCell is “2”,and the TDD UL-DL configuration of the SCell is “1”, the uplink subframein the PCell has a subframe number 2 or 7. With reference to Table 2, ifthe TDD UL-DL configuration is “2”, PDSCH A/N can be transmitted in thesubframe number 2 or 7; and if the TDD UL-DL configuration is “5”, PDSCHA/N can be transmitted in the subframe number 2. Therefore, the TDDUL-DL configurations 2 and 5 can be SCell reference TDD configurations.

The transmission/reception point selects an SCell reference TDDconfiguration specific to a user equipment from one or more SCellreference TDD configurations in operation S1230.

If one or more SCell reference TDD configurations identified in theoperation S1220 include the TDD UL-DL configuration of the SCell, theSCell reference TDD configuration specific to a user equipment may bethe TDD UL-DL configuration of the SCell. For example, if the TDD UL-DLconfiguration of the PCell is “1”, and the TDD UL-DL configuration ofthe SCell is “2”, the SCell reference TDD configuration may be a TDDUL-DL configuration 1, 2, 4, or 5, and the SCell reference TDDconfiguration specific to the user equipment can be 2, which is the TDDUL-DL configuration of the SCell. In general, if the uplink subframes ofthe PCell include all of the PDSCH A/N transmission subframes of theSCell, the SCell reference TDD configuration specific to the userequipment can be the TDD UL-DL configuration of the SCell.

If one or more SCell reference TDD configurations identified in theoperation S1220 do not include the TDD UL-DL configuration of the SCell,the transmission/reception point may select the SCell reference TDDconfiguration specific to the user equipment according to a certainpolicy. For example, if the channel environment of the correspondinguser equipment is not good, the transmission/reception point may selectan SCell reference TDD configuration having as many uplink subframes forPDSCH A/N timings as possible. If the channel environment of thecorresponding user equipment is good, the transmission/reception pointmay select an SCell reference TDD configuration having as few uplinksubframes for PDSCH A/N timings as possible. If the TDD UL-DLconfiguration of the PCell is “2” and the TDD UL-DL configuration of theSCell is “1”, the SCell reference TDD configuration may be a TDD UL-DLconfiguration 2 or 5, and the transmission/reception point may selectone from the TDD UL-DL configurations 2 and 5.

Further, the transmission/reception point transmits the SCell referenceTDD configuration specific to the user equipment to the user equipmentin operation S1240.

The information transmitted from the transmission/reception point to theuser equipment can be a value of an SCell reference TDD configuration.Further, the information transmitted from the transmission/receptionpoint to the user equipment can be an offset of the SCell reference TDDconfiguration from the TDD UL-DL configuration of the PCell or theSCell. Further, the information transmitted from thetransmission/reception point to the user equipment can be the index ofthe SCell reference TDD configuration specific to the user equipmentamong one or more possible SCell reference TDD configurations.

FIG. 13 is a diagram illustrating a method of transmitting PDSCH A/N ofa user equipment according to an exemplary embodiment of the presentinvention.

With reference to FIG. 13 , the method of transmitting PDSCH A/N of auser equipment includes receiving SCell reference TDD configurationinformation from a transmission/reception point (S1310), andtransmitting PDSCH A/N in a subframe determined according to a TDD UL-DLconfiguration of a PCell in case of the PCell and/or transmitting PDSCHA/N in a subframe determined according to an SCell reference TDDconfiguration of an SCell in case of the SCell (S1320).

The user equipment has configurations associated with a PCell and anSCell in a CA environment, and has information of the TDD UL-DLconfigurations of the PCell and the SCell through an upper layersignaling, such as system information (SI) and RRC.

The user equipment receives the SCell reference TDD configurationinformation from the transmission/reception point in operation S1310.The SCell reference TDD configuration information is transmitted throughRRC or PDCCH.

In case of the PCell, the user equipment determines an uplink subframe(timing) of the PCell for transmitting PDSCH A/N based on the TDD UL-DLconfiguration of the PCell and Table 2, and transmits PDSCH A/N of thePCell in the determined uplink subframe. In case of the SCell, the userequipment determines an uplink subframe (timing) of the PCell fortransmitting PDSCH A/N based on the SCell reference TDD UL-DLconfiguration and Table 2, and transmits PDSCH A/N of the SCell in thedetermined uplink subframe in operation S1320.

For example, it is assumed that the TDD UL-DL configuration of the PCellis 0 and the TDD UL-DL configuration of the SCell is 1. In such a case,the UL-DL configuration of the PCell is ‘DSUUUDSUUU’, the UL-DLconfiguration of the SCell is ‘DSUUDDSUUD’, and the subframe 4 and 9 areconflicting subframes. In such a case, the SCell reference TDDconfiguration is one of TDD UL-DL configurations 0, 1, 2, 3, 4, 5, and6. In an example, the SCell reference TDD configuration can be 1, whichis the same as the TDD UL-DL configuration of the SCell.

FIG. 14 is a diagram illustrating a case in which the TDD UL-DLconfiguration of the PCell is 0, the TDD UL-DL configuration of theSCell is 1, and the SCell reference TDD configuration is 1.

Since the PCell follows the TDD UL-DL configuration of the PCell, PDSCHA/N for PDSCH transmitted in the subframe 6 of the PCell in each radioframe can be transmitted in the subframe 2 of the PCell in the nextradio frame; PDSCH A/N for PDSCH transmitted in the subframe 0 of thePCell in each radio frame can be transmitted in the subframe 4 of thePCell in the same radio frame; PDSCH A/N for PDSCH transmitted in thesubframe 1 of the PCell in each radio frame can be transmitted in thesubframe 7 of the PCell in the same radio frame; and PDSCH A/N for PDSCHtransmitted in the subframe 5 of the PCell in each radio frame can betransmitted in the subframe 9 of the PCell in the same radio frame.

Since the SCell follows the SCell reference TDD configuration, PDSCH A/Nfor PDSCH transmitted in the subframes 5 and 6 of the SCell in eachradio frame can be transmitted in the subframe 2 of the PCell in thenext radio frame; PDSCH A/N for PDSCH transmitted in the subframe 9 ofthe SCell in each radio frame can be transmitted in the subframe 3 ofthe PCell in the next radio frame; PDSCH A/N for PDSCH transmitted inthe subframes 0 or 1 of the SCell in each radio frame can be transmittedin the subframe 7 of the PCell in the same radio frame; and PDSCH A/Nfor PDSCH transmitted in the subframes 4 of the SCell in each radioframe can be transmitted in the subframe 8 of the PCell in the sameradio frame.

In another example, it is assumed that the TDD UL-DL configuration ofthe PCell is 1, and the TDD UL-DL configuration of the SCell is 0. Insuch a case, the UL-DL configuration of the PCell is ‘DSUUDDSUUD’, andthe UL-DL configuration of the SCell is ‘DSUUUDSUUU’, and the subframes4 and 9 are conflicting subframes. In such a case, the SCell referenceTDD configuration may be one of TDD UL-DL configurations 1, 2, 4, and 5.

FIG. 15 is a diagram illustrating a case in which the TDD UL-DLconfiguration of the PCell is 1, the TDD UL-DL configuration of theSCell is 0, and the SCell reference TDD configuration is 2.

Since the PCell follows the TDD UL-DL configuration of the PCell, in thePCell, PDSCH A/N for PDSCH transmitted in the subframes 5 and 6 of thePCell in each radio frame can be transmitted in the subframe 2 of thePCell in the next radio frame; PDSCH A/N for PDSCH transmitted in thesubframe 9 of the PCell in each radio frame can be transmitted in thesubframe 3 of the PCell in the next radio frame; PDSCH A/N for PDSCHtransmitted in the subframe 0 or 1 of the PCell in each radio frame canbe transmitted in the subframe 7 of the PCell in the same radio frame;and PDSCH A/N for PDSCH transmitted in the subframe 4 of the PCell ineach radio frame can be transmitted in the subframe 8 of the PCell inthe same radio frame.

The SCell follows the SCell reference TDD configuration of the SCell. Inthe PCell, PDSCH A/N for PDSCH transmitted in the subframes 5 and 6 ofthe SCell in each radio frame can be transmitted in the subframe 2 ofthe PCell in the next radio frame. Since the subframes 4 and 8 of theSCell are uplink subframes, PDSCH A/N for PDSCH corresponding to thesubframes 4 or 8 of the SCell is not transmitted. PDSCH A/N for PDSCHtransmitted in the subframes 0 and 1 of the SCell in each radio framecan be transmitted in the subframe 7 of the PCell in the same radioframe. Since the subframes 9 and 3 of the SCell are uplink subframes,PDSCH A/N for PDSCH corresponding to the subframes 9 and 3 of the SCellis not transmitted.

FIG. 16 is a diagram illustrating a configuration of atransmission/reception point according to an exemplary embodiment of thepresent invention.

With reference to FIG. 16 , a transmission/reception point 1600 includesa controller 1610, a transmitter 1620, and a receiver 1630.

The controller 1610 selects a reference TDD configuration specific to auser equipment or an SCell reference TDD configuration. The userequipment and the transmission/reception point uses a CA technology thatperforms a communication using a plurality of CCs associated with thePCell and the SCell, and the controller 1610 selects the reference TDDconfiguration or the SCell reference TDD configuration for determiningtimings in which the user equipment transmits PDSCH A/N through thePCell if the TDD UL-DL configuration of the PCell and the TDD UL-DLconfiguration of the SCell are different from each other.

The controller 1610 identifies one or more reference TDD configurationsby using the TDD UL-DL configuration of the PCell, the TDD UL-DLconfiguration of the SCell, and Table 3. Further, with reference to FIG.6 , it is possible to identify one or more reference TDD configurationsthrough the operations S610 to S630 as described above. Further, thecontroller 1610 identifies one or more SCell reference TDDconfigurations based on the TDD UL-DL configuration of the PCell.

The controller 1610 may select the reference TDD configuration specificto the user equipment or the SCell reference TDD configuration from oneor more reference TDD configurations or SCell reference TDDconfigurations in consideration of the channel environment of the userequipment, the geographical location, or uplink transmission timing ofother information and signals.

The transmitter 1620 may transmit the reference TDD configurationspecific to the user equipment selected by the controller 1610 orinformation on the SCell reference TDD configuration to the userequipment. The transmission to the user equipment can be performedthrough RRC or PDCCH.

The receiver 1630 can receive uplink control information (UCI) thatincludes PDSCH A/N from the user equipment.

FIG. 17 is a block diagram illustrating a configuration of a userequipment according to an exemplary embodiment of the present invention.

With reference to FIG. 17 , a user equipment 1700 includes a controller1710, a transmitter 1720, and a receiver 1730.

In FIG. 17 , the user equipment 1700 uses a CA technology for performingcommunication with transmission/reception points by using a plurality ofCCs associated with PCells and SCells. The TDD UL-DL configuration ofthe PCell and the TDD UL-DL configuration of the SCell may be differentfrom each other.

The receiver 1730 may receive the reference TDD configurationinformation or the SCell reference TDD configuration information fromthe transmission/reception point through RRC or PDCCH.

The controller 1710 extracts information on uplink subframes (timings)for transmitting PDSCH A/N with respect to a PDSCH transmission on adownlink subframe and information on the downlink subframe in which thePDSCH is transmitted from the received reference TDD configurationinformation or the SCell reference TDD configuration information. Theinformation to be extracted can be extracted using the receivedreference TDD configuration information or the SCell reference TDDconfiguration information and Table 2.

If the receiver 1730 receives PDSCH, the controller 1710 generates anACK/NACK signal representing reception success/failure for the PDSCHtransmission, and controls the transmitter 1720 to transmit the ACK/NACKsignal through the PCell in the scheduled subframe (timing) so that thegenerated A/N (ACK/NACK signal) for the PDSCH may be transmitted.

In the illustrated exemplary embodiments, a description is made so thatthe transmission/reception point selects a reference TDD configurationspecific to the user equipment from the one or more possible referenceTDD configurations and transmits the selected information to the userequipment.

However, it is possible to select the reference TDD configurationspecific to the user equipment or the SCell reference TDD configurationfrom one or more possible reference TDD configurations or SCellreference TDD configurations according to rules defined in advance byeach of the transmission/reception point and the user equipment. In sucha case, the reference TDD configuration information or the SCellreference TDD configuration information may not be transmitted betweenthe transmission/reception point and the user equipment.

Further, it is possible to configure in advance a table including onlyone reference TDD configuration from among one or more possiblereference TDD configurations (or only one SCell reference TDDconfiguration from among one or more possible SCell reference TDDconfigurations) for each TDD UL-DL configuration pair of the PCell andthe SCell. That is, it is possible to set a configuration in advance inwhich one reference TDD configuration or one SCell reference TDDconfiguration will be used for each TDD UL-DL configuration pair of thePCell and the SCell. For example, if the TDD UL-DL configuration of thePCell in Table 3 is 0, and the TDD UL-DL configuration of the SCell is1, it is indicated that reference TDD configurations 1, 2, 4, and 5 arepossible as a reference TDD configuration, but one value configured inadvance among the possible values can be shown in the tables stored inthe transmission/reception point and the user equipment. In such a case,the reference TDD configuration information may not be transmittedbetween the transmission/reception point and the user equipment.

Further, if the TDD UL-DL configuration of the PCell and the TDD UL-DLconfiguration of the SCell are different from each other, it may bedefined in advance that a certain value (for example, the TDD UL-DLconfiguration 5) can be used for the reference TDD configuration or theSCell reference TDD configuration. In such a case, the reference TDDconfiguration information may not be transmitted between thetransmission/reception point and the user equipment.

In the illustrated exemplary embodiments, a description is made of acase in which one TDD UL-DL configuration of the PCell and one UL-DLconfiguration of the SCell are different from each other.

Meanwhile, a consideration may be made on a case in which the TDD UL-DLconfiguration of the PCell and a plurality of UL-DL configurations ofthe SCell, that is, three or more TDD UL-DL configurations, aredifferent from each other.

In such a case, the transmission/reception point compares the three ormore TDD UL-DL configurations in the operation S610 of FIG. 6 asdescribed above, and searches for one or more common uplink subframesfrom the three or more TDD UL-DL configurations in the operation S620,and identifies one or more reference TDD configurations that satisfy acondition that a set including uplink subframes of a reference TDDconfiguration for a PDSCH transmission is a subset of a set includingthe common uplink subframes in the operation S630. Thetransmission/reception point and/or the user equipment may include inadvance a table that shows the results obtained by the operationsdescribed above. Further, the common uplink subframes may berespectively obtained by identifying common uplink subframes between thePCell and each SCell and the common uplink subframes between the PCelland an SCell may be applied for the corresponding SCell, respectively.

Further, for PDSCH received from three or more CCs, the user equipmentcan transmit PDSCH A/N through uplink subframes of the PCell based onthe reference TDD configuration received from the transmission/receptionpoint or predefined in the user equipment.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A user equipment configured with at least twoserving cells, wherein said at least two serving cells comprise aprimary cell (PCell) and a secondary cell (SCell), the PCell and theSCell having different Time Division Duplex (TDD) Uplink-Downlink(UL-DL) configurations, the user equipment comprising: a receiverconfigured to receive a physical downlink shared channel (PDSCH)transmission on the SCell in a subframe ‘n−k_(i)’; a controllerconfigured to determine a reference TDD configuration for the SCell, thereference TDD configuration for the SCell being determined based on aPCell TDD UL-DL configuration and SCell TDD UL-DL configuration pair inTable 1-1 below: TABLE 1-1 Reference TDD configuration for SCellReference TDD (PCell TDD UL-DL configuration, configuration SCell TDDUL-DL configuration) 1 (1, 0), (1, 6), (0, 1), (6, 1) 2 (2, 0), (2, 1),(2, 6), (0, 2), (1, 2), (6, 2) 3 (3, 0), (3, 6), (0, 3), (6, 3) 4 (4,0), (4, 1), (4, 3), (4, 6), (0, 4), (1, 4), (3, 4), (6, 4), (3, 1), (1,3) 5 (5, 0), (5, 1), (5, 2), (5, 3), (5, 4), (5, 6), (0, 5), (1, 5), (2,5), (3, 5), (4, 5), (6, 5), (3, 2), (4, 2), (2, 3), (2, 4) 6 (6, 0), (0,6)

a transmitter configured to transmit a first acknowledgment/negativeacknowledgment (A/N) in an uplink subframe ‘n’, the first A/Ntransmitted in the uplink subframe ‘n’ being responsive the PDSCHtransmission received in the subframe ‘n−k_(i)’, wherein n, k and i areintegers, k_(i)∈K, a downlink set K for each reference TDD configurationbeing defined in Table 1-2, 0≤i≤M−1, M is the number of elements in thedownlink association set K. TABLE 1-2 Downlink association set index K:{k₀, k_(1 . . .) k_(M −) ₁} for TDD Reference TDD config- Subframe ‘n’uration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7,6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, — — 4, 6 3 — — 7, 6, 11 6, 5 5, 4 —— — — — 4 — — 12, 8, 7, 11 6, 5, — — — — — — 4, 7 5 — — 13, 12, 9, 8, —— — — — — — 7, 5, 4, 11, 6 6 — — 7 7 5 — — 7 7 —


2. The user equipment of claim 1, wherein the transmitter is configuredto transmit a second A/N in an uplink subframe determined by a referenceTDD configuration for the PCell, the second A/N being responsive to aPDSCH transmission on the PCell, wherein the reference TDD configurationfor the PCell is the PCell TDD UL-DL configuration.
 3. A method fortransmitting acknowledgement/negative acknowledgement (A/N) by a userequipment configured with at least two serving cells comprising aprimary cell (PCell) and a secondary cell (SCell), the PCell and theSCell having different Time Division Duplex (TDD) Uplink-Downlink(UL-DL) configurations, the method comprising: receiving a physicaldownlink shared channel (PDSCH) transmission on the SCell in a subframe‘n−k_(i)’; determining a reference TDD configuration for the SCell, thereference TDD configuration fir the SCell being determined based on aPCell TDD UL-DL configuration and SCell TDD UL-DL configuration pair inTable 3-1 below: TABLE 3-1 Reference TDD configuration for SCellReference TDD (PCell TDD UL-DL configuration, configuration SCell TDDUL-DL configuration) 1 (1, 0), (1, 6), (0, 1), (6, 1) 2 (2, 0), (2, 1),(2, 6), (0, 2), (1, 2), (6, 2) 3 (3, 0), (3, 6), (0, 3), (6, 3) 4 (4,0), (4, 1), (4, 3), (4, 6), (0, 4), (1, 4), (3, 4), (6, 4), (3, 1), (1,3) 5 (5, 0), (5, 1), (5, 2), (5, 3), (5, 4), (5, 6), (0, 5), (1, 5), (2,5), (3, 5), (4, 5), (6, 5), (3, 2), (4, 2), (2, 3), (2, 4) 6 (6, 0),(0,6)

transmitting a first acknowledgment/negative acknowledgment (A/N) in anuplink subframe ‘n’, the first A/N transmitted in the uplink subframe‘n’ being responsive the PDSCH transmission received in the subframe‘n−k_(i)’, wherein n, k and i are integers, k_(i)∈K, a downlink set Kfor each reference TDD configuration being defined in Table 3-2,0≤i≤M−1, M is the number of elements in the downlink association set K.TABLE 3-2 Downlink association set index K: {k₀, k_(1 . . .) k_(M −) ₁}for TDD Reference TDD Subframe ‘n’ configuration 0 1 2 3 4 5 6 7 8 9 0 —— 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — —8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6,5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, — — — — — — — 7, 5, 4, 11, 6 6 —— 7 7 5 — — 7 7 —


4. The method of claim 3, further comprising: transmitting a second A/Nin an uplink subframe determined by a reference TDD configuration forthe PCell, the second A/N being responsive to a PDSCH transmission onthe PCell, wherein the reference TDD configuration for the PCell is thePCell TDD UL-DL configuration.
 5. A transmission/reception facility thatcommunicates with a user equipment configured with at least two servingcells comprising a primary cell (PCell) and a secondary cell (SCell),the PCell and the SCell having different Time Division Duplex (TDD)Uplink-Downlink (UL-DL) configurations, the transmission/receptionfacility comprising: a controller configured to determine a referenceTDD configuration for the SCell, the reference TDD configuration for theSCell being determined based on a PCell TDD UL-DL configuration andSCell TDD UL-DL configuration pair in Table 5-1 below: TABLE 5-1Reference TDD configuration for SCell Reference TDD (PCell TDD UL-DLconfiguration, configuration SCell TDD UL-DL configuration) 1 (1, 0),(1, 6), (0, 1), (6, 1) 2 (2, 0), (2, 1), (2, 6), (0, 2), (1, 2), (6, 2)3 (3, 0), (3, 6), (0, 3), (6, 3) 4 (4, 0), (4, 1), (4, 3), (4, 6), (0,4), (1, 4), (3, 4), (6, 4), (3, 1), (1, 3) 5 (5, 0), (5, 1), (5, 2), (5,3), (5, 4), (5, 6), (0, 5), (1, 5), (2, 5), (3, 5), (4, 5), (6, 5), (3,2), (4, 2), (2, 3), (2, 4) 6 (6, 0), (0, 6)

a receiver configured to receive a first acknowledgment/negativeacknowledgment (A/N) from the user equipment in an uplink subframe ‘n’,the first A/N transmitted in the unlink subframe ‘n’ being responsive aPDSCH transmission in the subframe ‘n−k_(i)’, wherein n, k and i areintegers, k_(i)∈K, a downlink set K for each reference TDD configurationbeing defined in Table 5-2, 0≤i≤M−1, M is the number of elements in thedownlink association set K. TABLE 5-2 Downlink association set index K:{k₀, k_(1 . . .) k_(M −) ₁} for TDD Reference TDD Subframe ‘n’configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — —— 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 55, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — — 5 — — 13, 12,9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —


6. The transmission/reception facility of claim 5, wherein the receiveris configured to receive a second A/N from the user equipment in anuplink subframe determined by a reference TDD configuration for thePCell, the second A/N being responsive to a PDSCH transmission on thePCell, wherein the reference TDD configuration for the PCell is thePCell TDD UL-DL configuration.
 7. A method for receivingacknowledgement/negative acknowledgement (A/N) by atransmission/reception facility that communicates with user equipmentconfigured with at least two serving cells comprising a primary cell(PCell) and a secondary cell (SCell), the PCell and the SCell havingdifferent Time Division Duplex (TDD) Uplink-Downlink (UL-DL)configurations, the method comprising: determining a reference TDDconfiguration for the SCell, the reference TDD configuration for theSCell being determined based on a PCell TDD UL-DL configuration andSCell TDD UL-DL configuration pair in Table 7-1 below: TABLE 7-1Reference TDD configuration for SCell Reference TDD (PCell TDD UL-DLconfiguration, configuration SCell TDD UL-DL configuration) 1 (1, 0),(1, 6), (0, 1), (6, 1) 2 (2, 0), (2, 1), (2, 6), (0, 2), (1, 2), (6, 2)3 (3, 0), (3, 6), (0, 3), (6, 3) 4 (4, 0), (4, 1), (4, 3), (4, 6), (0,4), (1, 4), (3, 4), (6, 4), (3, 1), (1, 3) 5 (5, 0), (5, 1), (5, 2), (5,3), (5, 4), (5, 6), (0, 5), (1, 5), (2, 5), (3, 5), (4, 5), (6, 5), (3,2), (4, 2), (2, 3), (2, 4) 6 (6, 0), (0, 6)

receiving a first acknowledgment/negative acknowledgment (A/N) from theuser equipment in an uplink subframe ‘n’, the first A/N transmitted inthe uplink subframe ‘n’ being responsive a PDSCH transmission in thesubframe ‘n−k_(i)’, wherein n, k and i are integers, k_(i)∈K, a downlinkset K for each reference TDD configuration being defined in Table 7-2,0≤i≤M−1, M is the number of elements in the downlink association set K.TABLE 7-2 Downlink association set index K: {k₀, k_(1 . . .) k_(M −) ₁}for TDD Reference TDD Subframe ‘n’ configuration 0 1 2 3 4 5 6 7 8 9 0 —— 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — —8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6,5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 —— 7 7 5 — — 7 7 —


8. The method of claim 7, further comprising: receiving a second A/Nfrom the user equipment in an uplink subframe determined by a referenceTDD configuration for the PCell, the second A/N being responsive to aPDSCH transmission on the PCell, wherein the reference TDD configurationfor the PCell is the PCell TDD UL-DL configuration.